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Washington Laboratories (301) 417-0220 web: www.wll.com7560 Lindbergh Dr. Gaithersburg, MD 20879 1 Overview of RF Exposure Regulations for North America.

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Presentation on theme: "Washington Laboratories (301) 417-0220 web: www.wll.com7560 Lindbergh Dr. Gaithersburg, MD 20879 1 Overview of RF Exposure Regulations for North America."— Presentation transcript:

1 Washington Laboratories (301) 417-0220 web: www.wll.com7560 Lindbergh Dr. Gaithersburg, MD 20879 1 Overview of RF Exposure Regulations for North America

2 Credits The following presentation has come almost exclusively from the FCC/TCB Training session of October, 2005. This presentation is used for training of new TCBs in RF Exposure regulations. Additional materials have been added for clarity.

3 References to FCC Rules In many cases specific references to FCC rules. This is a very technical presentation and it is highly recommended that the most recent rules be followed carefully These rules can be found online at:


5 RF Exposure Requirements Exposure Standards oANSI/IEEE C95.1-1992 oNCRP Report No. 86 FCC Proceedings oET Docket 93-62 oFCC 96-326: Report & Order oFCC 96-489: 1 st MO&O oFCC 97-303: 2 nd MO&O oET Docket 03-137 oFCC 03-132: NPRM

6 Rules & Procedures FCC Rules: 47 CFR oLicensed & Unlicensed transmitters o§1.1307: fixed facilities o§2.1091: mobile installations o§2.1093: portable operations FCC documents oOET Bulletin 65: overall requirements oSupplement A: fixed transmitters oSupplement B: amateur radio oSupplement C: mobile & portable devices oOET Bulletin 56: consumer FAQ

7 Operating Conditions Fixed facilities: §1.1307 (MPE) oantennas on outdoor permanent structures owhole body exposure in far-field conditions obroadcast towers, basestations etc. Mobile installations: §2.1091 (MPE @ 20 cm) oantennas on non-permanent objects & structures opartial body exposure between near to far field conditions ovehicle-mounted antennas, desktop configurations etc. Portable operations: §2.1093 (SAR @ < 20 cm) odevices at close proximity to persons olocalized exposure in near-field conditions owireless handsets, Wi-Fi products etc.

8 Exposure Conditions Occupational / Controlled Exposure omust be work related or transient in nature operson must be fully aware of exposure operson must have knowledge to control & limit exposure orequire RF exposure training ohigher exposure limits apply General Population / Uncontrolled Exposure oall other situations oapply to all consumer devices ono knowledge of exposure required omore restrictive exposure limits apply

9 Time Averaged Exposure Occupational / Controlled exposure conditions oany 6-minute duration for both MPE (and SAR) ooperational based duty factor is acceptable General Population / Uncontrolled exposure conditions ofixed installations oany 30-minute duration with respect to MPE limits omobile and portable operating conditions ooperational duty factors do not apply osource-based time-averaging is acceptable oinherent to hardware design or transmission protocol omay include certain hardware or firmware restrictions

10 MPE

11 SAR

12 Routine Evaluation Potentials for exposure usually vary with operating configurations & exposure conditions Potential for exceeding limits may orequire routine evaluation to demonstrate compliance oallow certain operations to be categorically excluded from routine evaluation Routine evaluation is required according to oTable 1 of §1.1307 for fixed facilities o§2.1091(c) for mobile operations o§2.1093(c) for portable devices Evaluation may be triggered by §1.1307(c) or (d)

13 RF Exposure Labels Labels must be legible and clearly visible for the exposed persons to meet exposure requirements Labels may be used to identify RF exposure training material for satisfying occupational use conditions For general population exposure conditions olabels generally do not substitute for routine evaluation odevice should demonstrate compliance for normal operations without use of labels olabels may apply to certain unintended and mostly intermittent conditions of increased potential for exposure ooperating instructions and caution statements should be included in manuals to alert users about proper operation

14 Fixed Transmitter Sites Fixed transmitters operate at different frequencies may be collocated on towers and buildings etc. oexposure depends on the antenna configuration at a site ocompliance is usually determined at the time of licensing according to §1.1307(b)(3 ) RF exposure labels are required for subscriber transceivers - BRS, EBS, LMDS AND DEMS Compliance for both general population and occupational limits are required Unlicensed PCS and NII devices must use general population limits; occupational limits do not apply

15 Mobile Operations Mobile configurations require antennas & radiating structures to operate at 20 cm from persons during normal use Routine evaluation is required according to §2.1091 o> 1.5 W ERP @ 3.0 W ERP @ 1.5 GHz Evaluation may include ofield strength and/or power density measurements ocomputational modeling oestimations based on certain simple & generic exposure conditions Different time averaging requirements apply for general population and occupational exposure conditions Additional considerations are required for collocated transmitters that may transmit simultaneously

16 Typical Mobile Configurations Vehicle-mounted antennas ooccupational vs. general population exposure conditions owork-related operator vs. passengers & nearby persons Independent and embedded consumer devices otypical desktop and similar devices odesktop and laptop (display only) computer configurations ocompliance requires proper installation Marine radios operating on various size vessels osmall boats vs. large ocean liners omobile vs. fixed configurations

17 Collocated Mobile Devices Independent without simultaneous transmission Simultaneous or overlapping transmissions oat single or multiple frequencies ofrom single or multiple antennas at close proximity Determine compliance according to §1.1307(b)(3) oapply frequency dependent MPE limits and compute the sum of MPE ratios (MPE/MPE limit at each frequency) oinclude applicable source-based time-averaging odetermine minimum separation boundary ( 20 cm) according to output power and spatial separations among antennas

18 SAR Measurement Overview 1) computer for data recording5) ambient field 2) data acquisition unit6) phantom shell with tissue simulating liquid 3) dosimetric E-field probe7) device under test 4) probe positioner8) device positioner

19 Field Probe Construction Miniature E-field probes with 3 orthogonal dipole sensors operating with diode detectors for evaluating the SAR of low power devices |E| = (|E 1 | 2 + |E 2 | 2 + |E 3 | 2 ) ½ = (v 1 / 1 + v 2 / 2 + v 3 / 3 ) ½

20 SAR = |E| 2 / = c T/ t Frequency and tissue dielectric property dependent Calibration point is at geometric center of sensors osensors are not at probe tip and are offset from probe axis Probe calibration procedures for 0.3-3 GHz are described in IEEE Standard 1528 Probes should be calibrated in gradient fields using otemperature rise technique - < 800 MHz owaveguide technique - 800 MHz Field Probe Calibration

21 IEEE Standard 1528 SAM head phantom for testing handsets next to the ear Flat phantom for system validation and testing other operating configurations Phantom shell dielectric properties, shape and dimensions are fully defined in Standard 1528 Homogeneous tissue-equivalent liquids are used Tissue dielectric parameters are defined Currently no hand phantom available Phantom Requirements

22 ERP EEC - entrance to ear canal 15 mm M B LE F ERP - ear reference point EEC M B -30 N F +30 0 +20 0 -60 RE (ERP) 10 mm square N SAM Phantom Definitions

23 shell thickness –bottom: > 800 MHz - 2.0 0.2 mm with < 1% sagging (of λ air ) 800 MHz - < 6.5 0.2 mm with < 0.5% sagging (of λair) –other regions: unspecified length and width: 0.6 liquid depth: 15.0 0.5 cm shell material: r < 5.0 and loss tangent < 0.05 200 mm Flat Phantom Definitions

24 Tissue Dielectric Properties

25 Tissue Property Measurements IEEE 1528 recommended procedures oliquid filled Coaxial slotted line oCoaxial probe in liquid oliquid filled TEM-Line Sensors are connected to network analyzer dielectric constant and conductivity are calculated from reflection coefficients measuring standard liquids to verify accuracy 5% measurement uncertainty required

26 Measured SAR within 10% of target values SAR System Verification

27 Reference Dipoles

28 Dipole Reference SAR Values

29 Typical Test Configurations SAR is typically tested on high, middle & low channels Handsets are usually tested on the left and right side of the SAM phantom in cheek touching and 15º tilt positions with antenna extended and retracted, as appropriate tests are repeated for all operating modes and frequency bands with certain exceptions Other configurations are generally tested on high, middle & low channels with the device positioned at a appropriate distance from a flat phantom

30 Area scan to determine peak SAR locations opeak SAR mostly near surface of homogeneous phantoms oprobe boundary effects error requires probe tip location o> ½ probe diameter distance from phantom surface otypical scan resolution o1-2 cm at 3 GHz omeasured values are interpolated to identify peak locations zoom scan to determine volume averaged SAR otypical scan configurations o5 x 5 x 7 points in 3 x 3 x 3 cm 3 volume at < 3 GHz o7 x 7 x 7 or more points at 3-6 GHz o1-g SAR is computed by oextrapolating measured values to the phantom surface ointerpolating and then integrating with respect to a 1 cm 3 SAR Scan Procedures

31 SAR Measurement Uncertainty Identifies the probability of a measured value from its true value Standard uncertainty of an uncertainty component otype A - statistical analysis of a series of observations oestimating the standard deviation otype B - other than statistical analysis obased on scientific judgement - reference data and specifications Combined standard uncertainty oestimate the standard deviation by combining standard uncertainties using the root-sum-squares method Expanded uncertainty omultiplied the combined uncertainty by a coverage factor –defines the probability of the measured result in an interval where the true value is believed to be

32 Simultaneous Transmission SAR measurements are frequency dependent due to oprobe calibration requirements otissue dielectric parameters Simultaneous transmission at multiple frequencies requires SAR to be evaluated independently for each frequency using appropriate probe calibration and tissue dielectric parameters in identical device positioning conditions; i.e. measurement registration The results can be summed grid by grid according to the same measurement scan setup, followed by interpolation and extrapolation to compute 1-g SAR

33 TCB RF Exposure Qualification TCB training on SAR and general RF exposure procedures required to qualify for RF exposure scope Training material may include : oinformation and videos available for previous trainings oSupplement C, IEEE Standard 1528 and other related standards osummary and updates provided in current workshop oall other necessary updates on FCC rules, administrative policies and equipment certification procedures available from the FCC (knowledge database) and through the TCB council Attend additional trainings in future workshops on updates and new procedures to maintain qualification

34 Other Considerations Modular approval of unlicensed transmitters osee Public Notice DA 00-1407 3-6 GHz SAR requirements - pending Digital technology – Wi-Fi, Wi-Max, 3-G protocols Permissive Change requirements: Class I, II, III Applying meaningful and acceptable grant comments and conditions Pending proceedings – ET Docket 03-137 ofixed transmitters omobile and portable modules (§§ 15.247 and 15.407)









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